1. Field
The following description relates to image correcting methods and apparatuses for removing speckles from an image.
2. Description of the Related Art
Methods and apparatuses for observing inner structures of subjects such as human tissues or various materials are being widely used in various fields. Some examples are various kinds of internal transmitting images and tomography photographing equipment, such as an X-ray system, a computerized tomography (CT) scanner, a magnetic resonance imaging (MRI) apparatus, and an ultrasound system. Such equipment are used in the medical field because they identify cause, position, and progression of various kinds of diseases without cutting an inner structure of a human body or a living body. These diagnosis equipment are less harmful to a living body, provide a high-resolution image at a reasonable price, are mobile, and convenient to use. One such equipment, an optical coherence tomography (OCT) apparatus, uses interference between a light, which is irradiated to and reflected from a subject, and a reference light to capture an image of an inner structure of the subject. OCT provide high-resolution images, is harmless to a human body, and is widely used in the medical field due to its advantages.
Some methods of removing speckles from 2D ultrasonic images are described below. Since speckles occur by interference between reflective signals of adjacent reflectors, it is possible to decrease the speckles by decomposing signals generated from the reflectors. In addition, different ultrasonic images that represent the same position are obtained and shape deformation of the speckles on each ultrasonic image is averaged so that it is possible to reinforce image information on the tissues and to decrease the speckles. Moreover, it is possible to decrease speckles in an image by digital filtering, which may be implemented as a multi-scale technique using wavelet transform, which is a technique using a partial differential equation and a non-local means (NLM) technique using a mean of pixels adjacent to a current pixel in an image.